Elastomeric dielectric polymer film sonic actuator

• US 7,062,055 B2
• Filed: 10/26/2001
• Issued: 06/13/2006
• Est. Priority Date: 02/07/1997
• Status: Expired due to Term

• Current Assignee: SRI International, Inc.
• Original Assignee: SRI International, Inc.
• Inventors: Kornbluh, Roy D., Eckerle, Joseph S., Pelrine, Ronald E.
• Primary Examiner(s): LE, HUYEN D
• Application Number:
  US10/047,485
• Publication Number:
  US 20020122561A1
• Time in Patent Office: 1,691 Days
• Field of Search: 381/174, 381/191, 381/113, 381/116, 381/190, 381/173, 367/170, 367/181, 307/400, 29/254.1, 29/254.2, 310/800
• US Class Current: 381/191
• CPC Class Codes: F02G 2243/52 acoustic
• CPC Class Codes: F04B 35/045 using solenoids
• CPC Class Codes: F04B 43/043 Micropumps
• CPC Class Codes: H04R 17/005 using a piezoelectric polymer
• CPC Class Codes: H04R 17/08 signals being recorded or played back by vibration of a stylus in two orthogonal directions simultaneously
• CPC Class Codes: H04R 19/02 Loudspeakers H04R19/01 takes precedence
• CPC Class Codes: H04R 23/00 Transducers other than those covered by groups H04R9/00 - H04R21/00 diaphragms for transducers of the distributed-mode type H04R7/045
• CPC Class Codes: H04R 2499/13 Acoustic transducers and sound field adaptation in vehicles
• CPC Class Codes: H04R 5/02 Spatial or constructional arrangements of loudspeakers

Abstract

A sonic actuator including a multi-layer membrane having a non-metallic elastomeric dielectric polymer layer with a first surface and a second surface, a first compliant electrode layer contacting the first surface of the polymer layer, and a second compliant electrode layer contacting the second surface of the polymer layer. The actuator further includes a support structure in contact with the sonic actuator film. Preferably, the non-metallic dielectric polymer is selected from the group consisting essentially of silicone, fluorosilicone, fluoroelastomer, natural rubber, polybutadiene, nitrile rubber, isoprene, and ethylene propylene diene. Also preferably, the compliant electrode layer is made from the group consisting essentially of graphite, carbon, and conductive polymers. The support structure can take the form of grid having a number of circular apertures. When a voltage is applied to the electrodes, portions of the film held at the aperture of the support structure can bulge due to the electrostriction phenomenon. The resultant “bubbles” can be modulated to generate sonic vibrations, or can be used to create a variable surface for airflow control.

Claims

1. A sonic actuator comprising:

a multi-layer membrane including an elastomeric dielectric polymer layer having a first surface and a second surface;

a first complaint electrode layer contacting said first surface;

and a second complaint electrode layer contacting said second surface;

and a support structure in contact with the multi-layer membranes,

wherein the polymer layer is arranged in a manner which causes a portion of the polymer layer to deform in response to a change in electric field that is applied via at least one of the first compliant electrode layer or the second compliant electrode layer and wherein a portion of the polymer layer is capable of a strain of greater than 25% between a first position of the elastomeric dielectric polymer layer with a first area and a second position of the elastomeric dielectric polymer layer with a second area.

2. A sonic actuator as recited in claim 1 wherein said dielectric polymer is selected from the group consisting essentially of silicone, fluorosilicone, fluoroelastomer, natural rubber, polybutadiene, nitrile rubber, isoprene, and ethylene propylene diene.

3. A sonic actuator as recited in claim 1 wherein said complaint electrode layer is made from the group consisting essentially of graphite, carbon, and conductive polymers.

4. A sonic actuator as recited in claim 1 wherein said support structure is a grid having a plurality of apertures.

5. A sonic actuator as recited in claim 4, wherein the apertures are one of rectangularly-shaped, square-shaped or circularly shaped.

6. A sonic actuator as recited in claim 4 wherein said multi-layer membrane is biased such that portions of said membrane bulge at least some of said apertures.

7. A sonic actuator as recited in claim 6 wherein said multi-layer membrane is biased such that portions of said membrane bulge in a first direction at some of said apertures and such that portions of said membrane bulge in a second direction at others of said apertures.

8. A sonic actuator as recited in claim 7 wherein said membrane is biased by a gaseous pressure that is greater than atmospheric pressure where said membrane is bulging in a first direction, and is biased by a gaseous pressure that is less than atmospheric pressure where said membrane is bulging in a second direction.

9. A sonic actuator as recited in claim 6 wherein said support structure is substantially planar proximate to said apertures and wherein said bulging portion of said membrane exhibit an out-of-plane deflection.

10. A sonic actuator as recited in claim 6 wherein said multi-layer membrane is biased such that portions said membrane bulge in a first direction at least some of said apertures.

11. A sonic actuator as recited in claim 10 wherein said membrane is biased by a gaseous pressure that is greater than atmospheric pressure.

12. A sonic actuator as recited in claim 10 wherein said membrane is biased by a gaseous pressure that is less that atmospheric pressure.

13. A sonic actuator as recited in claim 10 wherein said membrane is biased by a soft foam material.

14. A sonic actuator as recited in claim 13 wherein said soft foam material is a closed-cell foam with an average cell diameter substantially less than a diameter of said apertures.

15. A sonic actuator as recited in claim 1 wherein said multi-layer membrane comprises a sandwich structure having a plurality of layer of elastomeric dielectric polymers alternating with a plurality of layers of complaint electrodes.

16. A sonic actuator as recited in claim 1 further comprising a square root driver coupled to said first complaint electrode and to said second complaint electrode.

17. A sonic actuator as recited in claim 16 wherein said square root driver includes a summer adding a lower power input signal to an offset voltage and a square root generator coupled to an output of said summer.

18. A sonic actuator as recited in claim 17 further comprising a filter coupled to an output of said square root generator.

19. A sonic actuator as recited in claim 18 further comprising an amplifier coupled to an output of said filter to provide a signal to drive said multi-layer membrane.

20. A sonic actuator as recited in claim 1, wherein the polymer layer is transparent.

21. A sonic actuator as recited in claim 1, wherein the sonic actuator is one of rectangularly shaped, spherically shaped or cylindrically shaped.

22. A sonic actuator as recited in claim 1, wherein a membrane thickness of the polymer layer is less than about 100 micrometers.

23. A sonic actuator as recited in claim 1, wherein said sonic actuator is a component of one of a speaker or an automobile.